This invention relates to a chemical cleaning method for removing the scales or other materials deposited on the interior of a polymerization reactor which has been used in emulsion polymerization or suspension polymerization.
The conventional plant cleaning technique includes mechanical cleaning and chemical cleaning. The mechanical cleaning includes a high-pressure jet cleaning, blast cleaning, and pig cleaning. The chemical cleaning includes alkali cleaning, acid cleaning, and emulsion cleaning. The alkali cleaning is generally used for removing oils and fats by use of caustic soda, sodium carbonate, etc. The acid cleaning is usually used for cleaning and removing inorganic scales, etc., with hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.. The emulsion cleaning is suitable for cleaning and removing oils and fats with a surfactant, etc.
Among these methods, generally, the mechanical cleaning, in particular the high-pressure jet, is employed to remove scales deposited on the interior of a polymerization reactor such as the inside surface, an agitator, and baffle-plates. It is usually difficult, however, for the high-pressure jet cleaning to completely remove the scales. To completely clean the inside surface of the reactor in advance, it is necessary to apply scale deposition preventing agent having function of a chelate compound on the inside surface of an polymerization reactor. Thus the high-pressure jet cleaning cannot be used for such a purpose.